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Vintage Two Strokes / 1974 Yamaha SC500

« on: September 24, 2012, 04:09:42 AM »

I have a '74 ex hillclimber converted back to MXer also. They can be an addiction as I have a second disguised as parts stashed around the shop so the wife thinks there's only one.  If you can't locate parts email me and I may have alternative suggestions (bearings, seals, ?) or an extra in my cache. I have thicker head gaskets and made thicker base gaskets. After one seizing because a head stud stripped during my second ever moto, I removed the head studs. Drill the opening out to accept 12mm bolts. Then locktited them in. Then cut and ground off flush and drilled and tapped to accept original head studs. For some reason, the cylinder aluminum becomes unstable and the little studs pulled out. Make sure to follow the Yamaha bulletin about the ignition module, use a 1974, or use aftermarket ignition. The original had a massive advance curve giving the bike its bad*ss image. (deserved) If the auto compression release is attached, replace it with a bolt and copper gasket. My second race resulted in a small seizure scoring the piston when the spring gave up when the bike got hot. Don't mean to ramble but  you are motivated for great reasons and I'd love to hear about your progress. Your post is why I joined this blog. HAVE FUN!